1. Field of the Invention
This invention relates to color stabilized distillate fuel oils. More particularly, this invention relates to inhibiting color deterioration of distallate fuel oils, such as diesel fuel.
2. Description of the Prior Art
Various middle distillate fuel oils such as diesel fuel and kerosene tend, with time, to deteriorate. Discoloration of distillate fuel oils is objectionable for various reasons, including customers' preference for light colored fuel oils because discoloration may indicate that deterioration has occurred.
Suggestions of the prior art for stabilizing fuel oils include U.S. Pat. No. 2,672,408, Bonner, which discloses the use of oil-soluble water-insoluble amines, the general formula of which can be represented as: N(R).sub.3, wherein R can be hydrogen or the same or different hydrocarbon radicals with at least one R being a nonaromatic hydrocarbon radical, for protection of particular blends of liquid hydrocarbons against discoloration. U.S. Pat. No. 2,945,749, Andress, discloses the use of a tertiary alkyl, primary, monoamine having from about 4 to 24 carbon atoms and in which the primary nitrogen atom is directly attached to a tertiary carbon atom, for inhibiting fuel oil deterioration in storage. U.S. Pat. No. 3,049,414, Kruyff, discloses a process for stabilizing the color of gasoline comprising the steps of washing the gasoline with a liquid characterized as being free of heavy metals and capable of dissolving pyridine; washing with alkaline aqueous solution, characterized as being free of heavy metals; removing substantially all the free alkali; and then adding an organic nitrogenous base, all of whose carbon-carbon bonds are saturated. U.S. Pat. No. 3,186,810, Dunworth, discloses a distillate hydrocarbon fuel oil containing a certain oil-soluble, basic amino nitrogen-containing addition type copolymer and an N-substituted cyclohexylamine in which the substituents consist of 1 to 2 alkyl groups of 1 to 4 carbon atoms. Also, U.S. Pat. No. 3,336,124, Dunworth, discloses a distillate hydrocarbon fuel oil containing certain oil-soluble polymeric dispersants and an N-substituted cyclohexylamine in which the substituents consist of 1 to 2 alkyl groups of 1 to 4 carbon atoms.
Of primary interest is U.S. Pat. No. 3,490,882, Dunworth, which relates to stabilized petroleum distillate fuel oils containing N,N-dimethylcyclohexylamine, and optionally, an N,N'-di(orthohydroxyarylidene)-1,2-alkylenediamine. U.S. Pat. No. 3,640,692, Rakow, et. al., discloses a stabilized distillate hydrocarbon fuel oil composition comprising a major proportion of a distillate hydrocarbon fuel and a minor proportion of a stabilizer comprising (a) an additive selected from the group consisting of (1) an amide plus a Schiff base; (2) an amide containing a Schiff base group; and (3) an amide containing a Schiff base group in combination with either an amide or a Schiff base; and (b) a cyclohexylamine selected from the group consisting of N,N-dimethylcyclohexylamine and dicyclohexylamine. Also, U.S. Pat. No. 3,701,641, discloses a stabilized distillate hydrocarbon fuel oil composition comprising a major proportion of a distillate hydrocarbon fuel and a minor proportion of a stabilizing additive comprised of (a) a polyamine having 2 to about 6 amino groups and containing about 24 to 50 carbons; (b) N,N'-disalicylidine-1,2-propylenediamine, and (c) a cyclohexylamine selected from the group consisting of N,N-dimethylcyclohexylamine and dicyclohexylamine. Additionally, U.S. Pat. No. 3,818,006, Klemchuk, discloses the use of sundry substituted hydroxylamines for stabilizing diverse organic materials against oxidation.
Of particular interest is U.S. Pat. No. 4,440,625, Go et al., which teaches that hydrocarbon process equipment is protected against fouling by incorporating into the hydrocarbon being processed small amounts of a composition comprised of a dialkylhydroxylamine and an organic sufactant. Moreover, U.K. Pat. No. 2,157,670, Nemes et al., discloses a composition containing a hydroxylamine compound; a quinone, a dihydroxylbenzene, or an aminohydroxybenzene compound; and a neutralizing amine which is useful as an oxygen scavenger and corrosion inhibitor in boiler water and other aqueous systems. Additionally, U.S. Pat. No. 4,456,526, Miller et al., teaches that hydrocarbon process equipment is protected against fouling by incorporating into the hydrocarbon being processed small amounts of a composition comprised of a dialkylhydroxylamine and a tertiary alkyl-catechol. U.S. Pat. No. 4,509,952, relates to an alkyldimethylamine ranging from C.sub.4 -C.sub.20 alkyl which may be added to a distillate fuel as a stabilizer to prevent fuel oil degradation. However, none of these prior art references disclose the unique and effective mixture of a tertiary amine and a hydroxylamine in accordance with the instant invention for inhibiting color deterioration of distillate fuel oils.